Rubidium production

Which reaction dominates depends on the ambient temperature in the interaction region Below about 100 million K, the carbon process dominates, whereas above that temperature the neon process tends to produce the slow neutrons. Since temperatures are typically higher in stars with more mass—as higher gravitational force accelerates and heats the stellar material—the neon reaction is more likely to proceed in stars much heavier than the Sun. The temperature of a distant star cannot, however, be measured directly. Rubidium production happens to be sensitive to neutron density—which is determined by the neutron production process—and can therefore be a good indicator of which reaction prevails in particular stars, especially when viewed as a ratio with other available s-process elements like yttrium or strontium. 

By contrast, in the disk and halo of the Milky Way, some metal-poor stars that are also overabundant in rubidium relative to iron are confusingly deficient in only slightly heavier elements, such as yttrium and zirconium. This would seem to indicate that, in these particular stars, the rubidium production occurs via the r-process (see chapter 8), which is not capable of producing the heavier elements. 

At the present time, worldwide rubidium production is small. Currently more expensive than gold or platinum, rubidium finds little demand. Worldwide, only about 22 tons (20 metric tons) of cesium compounds are produced annually. Given the prevalence of sodium and potassium usage, production or use of either rubidium or cesium is not likely to increase. 

Consider file fission reaction in which U-235 is bombarded by neutrons. The products of the bombardment are rubidium-89, cerium-144, beta particles, and more neutrons. 

I. Sodium tetraphenylborate Na+ [B(C6H5)4] . This is a useful reagent for potassium the solubility product of the potassium salt is 2.25 x 10 8. Precipitation is usually effected at pH 2 or at pH 6.5 in the presence of EDTA. Rubidium and caesium interfere ammonium ion forms a slightly soluble salt and can be removed by ignition mercury(II) interferes in acid solution but does not do so at pH 6.5 in the presence of EDTA. 

Since, in both these reactions (i.e. KI or Rbl and Agl), product formation occurs on both sides of the original contact interface, it is believed that there is migration of both alkali metal and silver ions across the barrier layer. Alkali metal movement is identified as rate limiting and the relatively slower reaction of the rubidium salt is ascribed to the larger size and correspondingly slower movement of Rb+. The measured values of E are not those for cation diffusion alone, but include a contribution from... 

The development of chemistry itself has progressed significantly by analytical findings over several centuries. Fundamental knowledge of general chemistry is based on analytical studies, the laws of simple and multiple proportions as well as the law of mass action. Most of the chemical elements have been discovered by the application of analytical chemistry, at first by means of chemical methods, but in the last 150 years mainly by physical methods. Especially spectacular were the spectroscopic discoveries of rubidium and caesium by Bunsen and Kirchhoff, indium by Reich and Richter, helium by Janssen, Lockyer, and Frankland, and rhenium by Noddack and Tacke. Also, nuclear fission became evident as Hahn and Strassmann carefully analyzed the products of neutron-bombarded uranium. 

The molten metal ignites in sulfur vapour, and reacts with various forms of carbon exothermically, one product, the interstitial rubidium octacarbide, being pyrophoric. 

Rubidium chloride is used for the production of rubidium metal, which, in the liquid form, has a high heat transfer coefflcient, making it useful as a coolant (along with other alkali metals) for nuclear reactors. 

The carbonate salt also may be obtained by passing carbon dioxide through a solution of rubidium hydroxide in a fluorocarbon or nickel container. The solution is evaporated to yield the product carbonate. 

Preparation should be in nickel or silver containers because rubidium hydroxide attacks glass. The solution is concentrated by partial evaporation. The commercial product is usually a 50% aqueous solution. 

Alternatively, Rb sulfate may be obtained by treating a hot solution of rubidium aluminum sulfate (rubidium alum) with ammonia solution. Aluminum hydroxide precipitates. The product mixture is fdtered. The filtrate on evaporation crystaUizes rubidium sulfate. 

Hydrogenation of dibenzofuran over a platinum catalyst in acetic acid at 50°C and moderate pressure affords perhydrodibenzofuran. At higher temperatures and pressures with platinum or palladium catalysts the product is 2-biphenylol. When dibenzofuran is hydrogenated in ethanol over Raney nickel at 190°C and 200 atm for 23 h, the products isolated were perhydrodibenzofuran (36%), trans-2-cyclohexylcyclohexanol (27%), cis-2-cyclohexylcyclohexanol (20%), and dicyclohexyl (3%). When the hydrogenation, under these conditions, was terminated after the absorption of only 3 mol equiv of hydrogen, the only product detected was perhydrodibenzo-furan. ° Hydrogenation of dibenzofuran over a sodium-rubidium catalyst,... 

The hydrogenation of phenanthridine at 250 °C under pressure in the presence of a sodium-rubidium catalyst in benzene is reported to give octahydrophenanthridines. Acridine similarly forms a variety of reduction products (71JOC694). 

As discussed in the previous section, trace elements are essentially retained in the solid combustion products and, because many are present on the surfaces of the particles, they are potentially leachable. Our data show the elements Mo, As, Cu, Zn, Pb, U, Tl, and Se will be readily accessible for leaching. A significant fraction of the V, Cr, and Ni, and a minor proportion of the Ba and Sr will also be potentially leachable because of the surface association, but most of these elements appear to be located in particles and will be released more slowly as the dissolution of the glass and other phases takes place. Rubidium, Y, Zr, Mn, and Nb are contained almost entirely within the particles and dissolution is potentially slower. The extent to which elements are leached also depends on their speciation and solubility in the porewaters, and the pH exerts a major control. In oxidizing solutions, elements such as, Cd, Cu, Mn, Ni, Pb, and Zn form hydrated cations that adsorb onto mineral surfaces at higher pH values and desorb at lower pH values. In contrast, the elements As, U, Mo, Se, and V, under similar Eh conditions, form oxyanions that adsorb onto mineral surfaces at low pH values and desorb at higher values (Jones 1995). 

The supply and demand for rubidium compounds has grown steadily since the 1970s. In 1979 the U.S. demand was ca 1040 kg of contained rubidium (16), and total world demand was estimated at approximately twice that of the United States. Reserves of rubidium in North America are estimated at 2 x 103 kg the United States is 100% import-reliant for rubidium, and Canada is the principal source of the raw material (16). The demand for rubidium metal is small compared to the demand for rubidium compounds. Table 2 lists approximate prices of rubidium metal and rubidium compounds. Primary producers of rubidium are Cabot Performance Chemicals (Boyerstown, Pennsylvania), MSA Research Corporation (Callery, Pennsylvania), and CM Chemical Products, Inc. (Berkeley Heights, New Jersey). Research quantities of rubidium in standard and specialized ampuls are available from Strem Chemicals, Inc. (Newburyport, Massachusetts). 

Radioisotope generators provide a desirable alternative to cyclotrons for the production of short lived positron emitters. A fully automated microprocessor controlled generator system for obtaining 76 sec rubidium-82 is described in detail. 

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